We intend to conduct studies attempting to elucidate a role for plasminogen isozymes. We will examine synthesis and degradation rates of plasminogen isozymes in rats, rabbits, and chickens and examine the effect of epsilon-amino caproic acid and other analogues on these rates. We also intend to examine steady and presteady state kinetics on the plasmins obtained from the various plasminogen isozymes as well as the effect of anions and cations on the various plasmin kinetic parameters. We also will examine and compare the rates of activation of the various plasminogen isozymes and the effect of anions and cations on these rates. It is our feeling that important differences may exist in the kinetics of plasmin isozymes which would be revealed by studies of this type. These investigations would shed light on the possible role of the isozymes of plasminogen. We also intend to perform structural studies on streptokinase in an attempt to understand the properties of this molecule and to understand its interaction with some plasminogens. We plan to perform amino acid sequence studies on the molecule and then study the effect of chemical modifications on the interaction of streptokinase and plasminogen, on the immunological properties of streptokinase, and on its conformational properties.